I found that Should, when compared to Ought has some additional uses, in particular replacing "would" or similar, as a neutral joint of sentences, but I'm interested in differences in their fundamental meaning:

used to indicate obligation, duty, or correctness, typically when criticizing someone’s actions

Do they differ in subtle ways, like one being more official or feeling archaic or something like that?

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    I believe it's never wrong to use should instead of ought. So you should use should if you're unsure of the difference. Feb 11, 2013 at 20:12

3 Answers 3


I must disagree with both user37324 and NOAD.

A recent survey of literature and corpus study1 on this topic shows clearly:

  • that the factors favouring choice of ought to over should are syntactical rather than semantic, and
  • that ought to is found more often in speech than in writing, but
  • in all contexts, should is preferred, by factors ranging (depending mostly on syntactic context) from 1.9 to 12.6 to 1.

These findings for British English coincide with my own impressions of American use, and with the quantitative findings of American corpus studies. I do not hesitate to assert that the two terms are synonymous. Should may be used in any context where ought to may be used.

And since should is far more frequent, I believe that a Learner may safely eliminate ought to from his vocabulary altogether; using should rather than ought to will never be wrong—unless the Learner must conform to a contrary opinion expressed by an examiner or academic advisor!

1Cappelle, Bert and Gert Desutter. 2010. ‘Should vs. Ought to’. In: Bert Cappelle and Naoaki Wada (eds.), Distinctions in English Linguistics, Offered to Renaat Declerck. Tokyo: Kaitakusha, 92-126.

  • ngram shows an interesting trend: While "Should" was always more popular than "Ought", and their popularity graphs coincide, "Ought" is currently dying out. ("Should" loses popularity too, and I wonder in favor for what word?)
    – SF.
    Feb 13, 2013 at 9:22
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    @SF. 1)*Shall/should*, in other contexts, has given way to will/would, which colloquialization of written English now often reduces to 'll/'d. 2) All modals are losing ground to semi-modals. Feb 13, 2013 at 11:05

The NOAD has a note about when using ought, and when should:

Reserve ought for expressing obligation, duty, or necessity, and use should for expressing suitability or appropriateness.

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    Could you expand on that answer? Some examples?
    – SF.
    Feb 11, 2013 at 14:31
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    I actually hear it equally as much, if not more, the other way. "It ought to work" and "It should work" are pretty much synonymous. But then, "We ought to watch our kids" is less appropriate than "We should watch our kids". :P The latter being clearly more "obligation, duty, or necessity", that rather makes the NOAD's recommendation look a bit less than 100% correct... :P
    – cHao
    Feb 11, 2013 at 14:43
  • The word "should" is a participle of "shall", which (at least in VA, USA) is used to mean "must". That may factor in here.
    – cHao
    Feb 11, 2013 at 14:47
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    @cHao A “participle”? Really?
    – tchrist
    Feb 11, 2013 at 15:02
  • @tchrist: I may have used the wrong word there. It's actually the past tense. Wikipedia makes it a bit less than clear whether that's right, but that's the word that sprang to mind, and at first glance it seemed to fit.
    – cHao
    Feb 11, 2013 at 15:06

It refers to the purpose of speaker and the kind of sentence or context. Should to and ought to have similarities and differences in usage.

Should to:

  1. to lay a tentative obligation

    You should come to the party tomorrow.

  2. to express a probability

    They should be at their destination by now.

  3. 'evaluative' should

    It's strange that he should say such a thing.

In the first meaning, ought to and should are completely interchangeable: You ought to come to the party tomorrow.

In the second, ought to is theoretically possible, but is rarely used with this meaning. They ought to be at their destination by now.

In the third, ought to is not used. It's strange that he ought to say such a thing.

The difference between "ought to" and "should", when they mean "giving a suggestion", is better understood when you examine expressions and examples.

For example if I like a cake very much and I want to suggest someone to try it I would say:

"You ought to try this cake."

In this case if we use "You should try this cake"

it says not much about how strong I liked it.

If someone is leaving the house after the diner, a polite way to invite him again is

"You ought to visit us again."

In this case if we use

"You should visit us again",

it does not give that strong expectation. With "you ought to visit us again" you compliment to the person that has visited you far more than with "you should visit us again".

"ought to" is sometimes a synonym to "cannot avoid". "should" is almost never a synonym to "cannot avoid".

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